Rotorcraft Beam with Segmented Flexure and Shear Stiffness
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Solution Overview
Problem
Hingeless and bearingless rotors in rotorcrafts face challenges in reducing the virtual hinge offset, which affects the efficiency of blade movements and load distribution.
Innovation Solution
A beam design with specific flexure and shear portions that alter the virtual hinge location by varying bending and shear stiffness, allowing for reduced virtual hinge offset through controlled bending and shear deformations, applicable to both main and tail rotors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional beam designs are used in hingeless and bearingless rotors, then the structure can support blade loads and enable blade motions, but the virtual hinge offset cannot be reduced, affecting efficiency
Solution Approach 1:
The beam is divided into distinct functional portions: a hub connection portion, a first flexure portion with reduced bending stiffness, and a shear portion with reduced shear stiffness. This segmentation allows each portion to independently control specific deformation characteristics, enabling reduction of virtual hinge offset while maintaining load support capabilities.
Solution Approach 2:
Different portions of the beam are assigned different stiffness properties: the first flexure portion has bending stiffness smaller than both the hub connection portion and blade connection portion, while the shear portion has shear stiffness smaller than these same portions. This local differentiation of mechanical properties enables precise control over the virtual hinge location and blade movement efficiency.
2Strength
If the beam stiffness is increased to support higher loads, then load bearing capacity improves, but the virtual hinge offset increases, reducing blade movement efficiency
Solution Approach 1:
The beam is divided into distinct functional portions: a hub connection portion, a first flexure portion with reduced bending stiffness, and a shear portion with reduced shear stiffness. This segmentation allows each portion to independently control specific deformation characteristics, enabling reduction of virtual hinge offset while maintaining load support capabilities.
Solution Approach 2:
Different portions of the beam are assigned different stiffness properties: the first flexure portion has bending stiffness smaller than both the hub connection portion and blade connection portion, while the shear portion has shear stiffness smaller than these same portions. This local differentiation of mechanical properties enables precise control over the virtual hinge location and blade movement efficiency.
3Weight of moving object
If the beam is made thinner to reduce weight and size, then weight and dimensions decrease, but the beam loses sufficient bending and shear stiffness to support blade loads
Solution Approach 1:
The beam is divided into distinct functional portions: a hub connection portion, a first flexure portion with reduced bending stiffness, and a shear portion with reduced shear stiffness. This segmentation allows each portion to independently control specific deformation characteristics, enabling reduction of virtual hinge offset while maintaining load support capabilities.
Solution Approach 2:
The beam design modifies stiffness parameters locally by creating portions with controlled bending and shear stiffness characteristics. The first flexure portion has bending stiffness smaller than the hub connection and blade connection portions, while the shear portion has shear stiffness smaller than these same portions, enabling weight reduction without compromising overall structural integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The beam design reduces the virtual hinge offset, enhancing the efficiency of blade movements and load distribution, thereby improving the rotorcraft's performance and reducing weight and size.
Implementation Method 1
a first flexure portion located between the hub connection portion and the blade connection portion and having a bending stiffness about a first axis which is orthogonal to the longitudinal axis of the blade - when connected to the beam - smaller than that of the hub connection portion and that of the blade connection portion about the first axis
Implementation Method 2
a shear portion located between the hub connection portion and the blade connection portion and having a shear stiffness parallel to a second axis which is orthogonal to the longitudinal axis of the blade - when connected to the beam - and non-parallel, preferentially orthogonal to the first axis, said shear stiffness being smaller than that of the hub connection portion and that of the blade connection portion, in order to change the location of the virtual hinge that corresponds to the first flexure portion
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a beam (13) for a rotorcraft rotor and particularly to a helicopter rotor. Said beam (13) comprises a hub connection portion (14), a blade connection portion (15), a first flexure portion (16) located between the hub connection portion (14) and the blade connection portion (15) and having a bending stiffness about a first axis which is orthogonal to the longitudinal axis (X) of the blade (12), said bending stiffness being smaller than that of the hub connection portion (14) and that of the blade connection portion (15) and a shear portion (17) located between the hub connection portion (14) and the blade connection portion (15) and having a shear stiffness parallel to a second axis which is orthogonal to the longitudinal axis (X) of the blade (12) and non-parallel to the first axis. Said shear stiffness is smaller than that of the hub connection portion (14) and that of the blade connection portion (15).